The present invention relates to a hollow, rotary clamping apparatus which is hydraulically or pneumatically operable and which is primarily intended for powerful automatic latches.
A number of rotary hydraulic oil clamping or chucking devices are known which vary in structure but have one feature in common namely that the piston portion impacted by the pressure oil rotates and is connected directly to the actuating tube which acts on the collet or the like and the pressure medium is supplied via a labyrinth rotation transmitter. This arrangement produces a number of serious disadvantages. On the one hand the pressure oil is heated to a substantial extent which necessitates use of an oil cooler or heat exchanger and a considerable output is absorbed. Moreover a high rate of leakages occurs in all these known hydraulic clamping cylinders.
Pneumatically operated chucking devices which do not entail the known disadvantages achieve only moderate clamping forces.